The present invention relates to a method for arranging a higher density and less expensive thermal-recording head.
The thermal recording system includes a recording unit operated in a serial printer or line printer mode.
The serial-printer-mode recording unit employs a recording head consisting of at most one hundred heating elements. The line-printer-mode recording unit, on the other hand, requires a recording head consisting of several thousands of heating resistive elements arranged in a line. In order to heat such a great number of heating elements in response to a recording signal, the following types of recording heads have been developed;
1. Diode Matrix Type
2. a first phase, this type of recording head has been employed in a facsimile machine. It results in giving an opportunity of developing a thermal recording system. The diode matrix type recording head is designed to use a group of 32 to 64 heating elements as a single unit for recording. It thus takes several hundred mm seconds to record one line. To reducing the recording time per line to several mm seconds by concurrently heating many heating elements, there have been the following types of systems developed: 2. Thyristor Array Type and 3. Semiconductor IC Mount Type. Today, the thermal recording system normally employs a semiconductor IC mount type for thermal printing.
Accompanying the improvement of the recording heads, relevant matters have been also developed such as arrangements of a recording unit, including how to contact a recording paper with a head and send a recording paper, improvement of color type thermal recording paper and development of transfer type recording paper. These developments have resulted in recognition of the thermal recording system as being easily handled and maintained and such systems have been commercially popular. The system thus applies to various kinds of fields such as:
(a) Facsimile using color type thermal paper and some kinds of printers; and PA1 (b) Monotone printer, and multi-color or full-color printer using heat fusion type or sublimation type imprint paper, image-receiving paper. PA1 100: Overall arrangement of the heating unit of the conventional recording head PA1 1: Heating element PA1 2: Common electrode PA1 3: Individual electrode PA1 4: Transistor PA1 6: Power source for energizing heating elements PA1 20: Semiconductor IC PA1 101: Conventional IC-type recording head circuit PA1 7: Power source for semiconductor IC PA1 20: Conventional semiconductor IC circuit PA1 11: shift register for transferring a recording signal PA1 12: latch circuit for temporarily storing a recording signal PA1 13: gate circuit for supplying a recording signal of a latch circuit PA1 4: transistor for supplying a recording output (actuating a heating element) PA1 recording head actuating terminal: 101a, c to 107. PA1 1. Diode Matrix Type PA1 2. Thyristor Array Type PA1 3. Semiconductor IC Mount Type PA1 (1) the high-density thermal recording head has a limitation to array density, that is, 16 dots per millimeter. To solve is shortcoming, the simultaneous formation of the heating elements and the semiconductor IC devices is being developed using a thin film forming technique but is still not put into practice; and PA1 (2) the connection between the heating elements and the semiconductor devices with a high-density lead line makes it difficult to lower the manufacturing cost of semiconductor IC-type head by the conventional manufacturing technique. PA1 (1) realization of a high-density recording head, and PA1 (2) reduction of the cost of the recording head, by lessening the quantity of semiconductor devices required for the recording head and lowering a density of connection between the heating elements and the semiconductor devices. PA1 (1) means for selecting a heating element one by one from among adjacent N heating elements and dividing all the heating elements into N groups, and PA1 (2) means for simultaneously heating selected one element of all the groups, whereby the heating elements arranged in one line are divided into N groups for recording.
FIGS. 1A to 1D show circuit arrangements of a recording pattern, arrangement of a heating section and an overall recording head used in a conventional semiconductor IC mount type recording head.
FIG. 1A shows a recording pattern used in the conventional recording head, wherein 18 resistive segments arranged in a line are divided in three groups for recording. In this Figure, one square corresponds to one recording dot and a numeral shown in the square indicates how to divide the heating segments for actuating them and a heating (=recording) order.
The conventional semiconductor IC mount type recording head, as shown in FIG. 1A, is designed to divide the eighteen resistive segments into three groups, each of which is a single recording unit consisting of adjacent six segments. Since the eighteen heating elements are arranged exactly in a line, the divisional recording system slightly shifts recording positions of second and third recorded dots relative to the recording position of the first recorded dots in the feeding direction of the recording paper.
FIG. 1B shows an arrangement of the heating unit of the conventional semiconductor IC mount type recording head.
In FIG. 1B, the numerals denote these portions or elements:
As shown in FIG. 1B, the heating unit of the conventional IC-type head is configured to connect a collector of each semiconductor IC transistor 4 to one end of each of the heating elements 1 arranged in a line, connect the other end of each heating elements 1 and an emitter of each transistor 4 to a power source 6 for actuating the heating elements and actuate each of N groups composed of all the heating elements in the order for recording. That is, in FIG. 1B, at first, recording signals are applied to the semiconductor ICs 20 so as to switch on the transistors 4 connected to the first to sixth heating elements 1 as viewed from the right. Next, by the succeeding operation, the seventh to twelfth and the thirteenth to eighteenth heating elements are actuated (heated). These operations result in providing a divisional recording pattern for one line of N=3 as shown in FIG. 1A.
FIG. 1C shows an example of overall circuit illustrating the conventional IC-type head, wherein:
The IC circuit 20 comprises:
The terminals of the semiconductor IC 20 are respectively connected to the eighteen elements 1 as shown for forming:
The terminals 104 and 105 are connected to the semiconductor IC power source 7.
The recording head is designed to apply a one-line recording signal to the terminal 101a, transfer the recording signal sequentially through the eighteen shift register circuits 11 in response to a clock signal from the terminal 101b, and temporarily store the recording signal transferred by a latch signal from the terminal 102 in the eighteen latch circuits 12.
In response to a gate signal applied to the terminal 103, the first to sixth transistors 4 as viewed from the right hand side become conductive in response to the recording signals stored in the corresponding latch circuits. Then, the six heating elements 1 connected to the conductive transistors 4 are heated up by the power source 6 for actuating the heating elements, the power source being connected to the terminals 106 and 107. Succeeding to a signal application to the terminals 103b and 103c, the seventh to twelfth and the thirteenth to eighteenth heating elements are heated up, resulting in the one-line recording as shown in FIG. 1.
During a period of recording one line, the next line signal is applied to the terminal 101a for preparing the succeeding next line recording. Likewise, the subsequent lines are recorded in the divisional recording mode. In addition, 104 and 105 denote semiconductor IC power terminals of the recording head.
The foregoing three types of recording heads:
have respective circuit arrangements according to the semiconductor devices connected to the heating elements. However, the feature of dividing the heating elements for one line recording as in FIGS. 1A and B is common to these three heads.
The shortcoming of the arrangement of the heating unit shown in FIG. 1B is to require connection of heating resistive elements to semiconductor devices (diode array, thyristor array or output transistor array) in one-to-one relationship by a high density lead line pattern. That is, the manufacture of a heating element actuating type recording head as shown in FIG. 1B becomes more difficult as the array density of the heating elements becomes higher.
For the above reason, today: